The present invention relates generally to integrated circuits, and in particular to programming circuits in a memory device.
Semiconductor memory devices such as dynamic random access memory (DRAM) devices are widely used to store data in computers and electronic products. A memory device typically has a number of memory banks. Each of the memory banks has a large number of memory cells to store the data. The memory cells are typically arranged in rows and columns.
A typical memory device also has a number of spare memory cells, which are used to replace defective memory cells. When a row or column of the memory cells is defective, the address of the defective row or column is programmed. During a memory operation, a controller of the memory device compares an input address of a row or column with the programmed address. A match between the input address and the programmed address means that the input address is the address of a defective row or column. In this case, the row or column of the spare memory cells are accessed instead of the defective row or column.
The address of the defective row or column is programmed in a number of programmable elements of the memory device. The memory device has a programming circuit connected to a programming input pad of the memory device. During a programming operation, a programming voltage is applied at the programming input pad. The programming circuit receives the programming voltage, which is used to program the programmable elements. The programming voltage causes the programmable elements to form a pattern representing an address of a defective row. In this type of memory device, the memory banks are usually located in the same general location and only one programming circuit is used for all the memory banks.
As design of memory devices advances, some memory devices are designed with a modular design approach. In this approach, a memory device has a number of memory banks or memory macros scattered in different locations; and each of the memory macros has its own programming circuit. Thus, in a modular design, the memory has multiple programming circuits. However, all of the multiple programming circuits still connect to the same programming input pad. Thus, during a programming operation, when one programming circuit receives the programming voltage applied at the programming input pad to program programmable elements of one corresponding memory macro, other programming circuits also receive the programming voltage even though they are not used or activated.
When a programming circuit is not used or activated but receives a programming voltage, the programming voltage can cause damage to internal components of the programming circuit. This can lead to damage or failure of the programming circuit.
There is a need for a method to protect the programming circuits from damage in a memory device having multiple programming circuits.
The present invention is a memory device having multiple programming circuits. The programming circuits are protected from damage during a programming operation.
In one aspect, the memory device includes an input pad to receive a programming voltage, and a plurality of memory macros. Each of the memory macros has memory cells and programmable elements. The memory device also includes a plurality of programming circuits connected between the input pad and the memory macros. Each of the programming circuits has a precharge circuit connected between the input pad and a programming node. Each of the programming circuits also has an enable circuit connected to the precharge circuit. The enable circuit includes an enable input to receive an enable signal. When the program enable signal is activated, the bootstrap-regulator circuit passes the programming voltage to the programming node to program the programmable elements. When the program enable signal is not activated, the bootstrap-regulator circuit passes only a part of the programming voltage to the programming node and the programmable elements are not programmed.
In another aspect, a method of programming a memory device includes activating one programming circuit among:a plurality of programming circuits. A programming voltage is applied to an input pad connected to all programming circuits. The activated programming circuit passes the programming voltage to a programming node connected to it. Other non-activated programming circuits pass only a portion of the programming voltage to programming nodes connected to them.